Security and Compliance at Service Boundaries

Trust boundaries become explicit when systems decompose. Chapter 15 focuses on how service identity, authorization, data sensitivity, tenant isolation, and audit evidence all change once one process becomes many separately owned boundaries.

Read the lessons in order. The first covers service-to-service authentication and authorization. The second explains how data classification changes boundary design. The third focuses on multi-tenant boundary pressure. The fourth shows how clearer boundaries help compliance ownership and audit evidence.

If a boundary is technically clean but still weak in identity, access control, or evidence of responsible operation, this chapter is where that gap becomes visible.

In this section

• Authentication and Authorization Between Services
  A practical lesson on service identity, workload authentication, token propagation, and least-privilege authorization between services in a distributed system.
• Data Classification and Sensitive Boundaries
  A practical lesson on how data sensitivity influences boundary design, including when stricter isolation, stronger controls, or separate services become justified.
• Boundary Design for Multi-Tenant Systems
  A practical lesson on how tenant isolation, data residency, and administrative scope pressure service boundaries in multi-tenant architectures.
• Compliance and Audit Responsibilities
  A practical lesson on how clear service boundaries support ownership, control mapping, evidence collection, and auditability in regulated or policy-heavy environments.